A light-emitting diode (LED) can be a semiconductor device that emits light when an electric current passes through it. LEDs are used in a wide variety of electronic devices. LEDs are typically sold in packages that include leads for connecting to an electrical source, an LED die for generating light, a casing, and an integral lens. These LED packages are then incorporated into various applications, such as signs or traffic signals.
Although LED packages are available in a variety of standard beam patterns, LED packages are not normally capable of capturing and focusing all of the light output from the LED die into a concentrated narrow beam, as may be desired for a signaling device or a high intensity display. Also, standard LED packages cannot normally produce light beams that are broad in one direction and narrow in another, nor produce beam patterns that are extremely broad (e.g. 180 degrees) in one or more directions with uniform or varying intensities over beam-width. Furthermore, most LED packages tend to “leak” light by allowing a portion of the radiated light from the die to radiate outside of the primary radiation pattern of the device.